Vitamin D may slash pancreatic cancer risk: Harvard study

Increased blood levels of vitamin D may decrease the risk of developing pancreatic cancer by an impressive 30%, according to a new Harvard-led study.

Data from over 1,500 people collected over 14 years indicated that people with vitamin D insufficiency were at a 30% increased risk of developing pancreatic cancer, compared with people with adequate levels of the sunshine vitamin.

Being an observational study, the results should be interpreted with caution, but they do add to the ever growing list of potential anti-cancer benefits of adequate vitamin D intake.

“In light of the high prevalence of vitamin D insufficiency in the population, further studies should examine whether increasing vitamin D levels impacts the incidence of this highly lethal malignancy,”​ wrote the researchers, led by Brian Wolpin from the Dana-Farber Cancer Institute and Harvard Medical School.

Pancreatic cancer is the fourth leading causing of cancer death (about 37,500 per year) in the US, according to the Pancreatic Cancer Action Network.

D and the big C​

The link between vitamin D intake and protection from cancer dates from the 1940s when Frank Apperly reported in Cancer Research a link between latitude and deaths from cancer, and suggested that sunlight gave "a relative cancer immunity"​.

Since then a raft of studies has floated down the science river reporting risk reductions for a range of cancers, including colorectal, breast, oral, stomach, and (as reported here) pancreatic.

Speaking with NutraIngredients-USA this spring​, Michael Holick, PhD, MD, Professor of Medicine at Boston University Medical Center and a world-renowned expert in vitamin D, said the association between high vitamin D levels and lower incidences of cancer continues, and he can see “no other explanation”​ than vitamin D reducing the incidence.

New data​

The new study adds to this association. Wolpin and his co-workers assessed levels of vitamin D in the form of 25-hydroxyvitamin D (25(OH)D) – the storage form of the vitamin in the body with the incidence of pancreatic cancer.

Data for 451 people with pancreatic cancer and 1,167 healthy ‘controls’ from five different cohorts was included in the study.

Results showed that average 25(OH)D levels were significantly lower in people with the cancer, compared with the controls.

In addition, mildly insufficient or sufficient blood levels of vitamin D, defined as 25(OH)D levels of at least 50 nmol/L, were associated with a 30% reduction in pancreatic cancer risk, compared with people with insufficient levels (less than 50 nmol/L).

Very high blood levels of vitamin D (at least 100 nmol/L) did not offer any additional risk reduction benefits, added Wolpin and his co-workers.

Biologically plausible? ​

Commenting on the potential mechanism, the researchers note that there is increasing support for a role of vitamin D in the development of cancer. Lab studies have indicated that pancreatic cancer cells can convert 25(OH)D to the active form of the vitamin (1,25-dihydroxyvitamin D or 1,25[OH]2D). These cells also express vitamin D receptors, which play a role in gene regulation.

“Thus, vitamin D receptors target genes may be regulated locally at the site of a developing cancer, with important implications for cellular proliferation, apoptosis, and angiogenesis,”​ they wrote.

Studies with mice have also indicated that vitamin D can slow the growth of pancreatic cancer cells.

“Clinical studies are underway to exploit these effects of vitamin D and its analogues in patients with pancreatic cancer,”​ wrote the researchers.